Due to the decreasing size of Unmanned Arial Vehicles (UAVs) and size and weight limitations on airborne platforms such as UAVs, equipment suppliers are often faced with requirements that constrain space and weight allowances available for electronics equipment. For example, in some airborne platform applications, only one antenna is allowed. Typically, this would have to be an antenna with an omnidirectional beam pattern. These antennas have low gain (normally 3 dB) and do not allow communication over long distances.
There are certain applications where a small, lightweight antenna that functions with both omni-directional low gain radiation and directional high gain radiation is desirable. One prior solution to this problem is to provide a circular horn array with 360 degree coverage. The horn array may be switched electronically to use fewer than all of the horns, thereby increasing gain. However, differences in impedance when in omni-mode (all horns active) and directional mode (one or two horns active) adversely impacts the Voltage Standing Wave Ratio (VSWR) and other performance characteristics.